Method of fabricating brake assembly

ABSTRACT

A method to fabricate an integrated elevator drive machine and brake assembly is disclosed. In the method, an outer wall segment of a drive machine housing is cast to form a base of a brake assembly. In casting the outer wall segment to form the base of the brake assembly, a metal blank of higher magnetic permeability is cast or embedded into the casing of the outer wall segment and is machined to form the base. Alternately, the casting of the outer wall segment may be dimensioned and configured so that the casting of the outer wall segment itself forms the base. The outer wall segment is secured for machining a bearing assembly counterbore and, without unsecuring the wall segment from the machining operation, the base of the disc brake assembly is machined to form the groove for housing a magnetic coil, a plurality of bores to house the brake springs, and a plurality of bolt bores. Precise relative alignment of the grooves, spring bores, stud bores, and bearing assembly counterbore is efficiently achieved by contemporaneous machining operations.

This is a division of copending application Ser. No. 08/415,829, filedon Apr. 3, 1995.

TECHNICAL FIELD

This invention relates to a brake assembly for an elevator drive machineand more particularly to an integrated elevator drive machine disc brakeassembly and method of fabrication.

BACKGROUND OF THE INVENTION

Elevators are presently provided with a plurality of braking deviceswhich are designed for use in normal operation of the elevator such asholding the cab in place when it stops at a landing and for use inemergency situations such as stopping the cab and/or counterweight fromplunging into the hoistway pit.

The normal operational brakes on geared elevator drive machines aretypically drum brakes which engage the machine input shaft to hold thelatter against rotation when the cab is stopped at a floor. Disc brakeshave been added to provide braking on the output shaft. Heretofore, discbrakes on the output shaft were utilized in addition to input shaftbrakes so that the elevator drive machine had both input shaft brakesand output shaft brakes. Commonly assigned U.S. Pat. No. 5,226,508entitled Disc Brake for Elevator Drive Sheave and granted Jul. 13, 1993to R. Ericson et al. discloses a disc brake assembly for retrofitmounting to the output shaft and sheave of an existing elevator drivemachine which has input shaft brakes. Commonly assigned U.S. Pat. No.5,201,821 entitled Disc Brake Elevator Sheave granted Apr. 13, 1993 toR. Ericson et al. discloses a disc brake assembly for incorporation innew equipment elevator machines which have input shaft brakes. It wouldbe desirable to provide a new and improved output shaft disc brakeassembly which obviates the need for input shaft brakes.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a new and improvedelevator drive machine having output shaft braking without input shaftbraking.

A further object of the invention is to provide an integrated elevatordrive machine and output shaft brake assembly.

Another object of the invention is to provide such an integrated brakeassembly which is cost efficient to manufacture and reduces the numberof component parts.

A further object of the invention is to provide such a brake assemblywhich is easy and convenient to service.

A still further object of the invention is to provide a new and improvedmethod of manufacture of such an integrate brake assembly.

A still further object of the invention is to provide an integrated discbrake assembly and method of manufacture that may be utilized in bothworm gear and helical gear elevator drive machines as well as gearlesselevator drive machines.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

Accordingly, it has been found that the foregoing and related objectsare attained and disadvantages of the prior art are overcome in anelevator drive machine having a machine housing with an outer wall, arotatable output shaft with a sheave mounted on it for rotationtherewith and a brake assembly for braking the output shaft and sheave.The brake assembly has a base integrally formed with the outer wall ofthe machine housing adjacent the output shaft. The machine housing maybe a casting and the metal base of the brake assembly is cast orembedded within the casting of the outer wall of the housing.Alternately, the outer wall of the machine housing is configured so thata predetermined portion of the casting of the outer wall forms the baseof the brake assembly. The integrally formed base has a groove forhousing the magnetic coil of a disc brake assembly. The base also has aplurality of bores for housing the brake springs and a plurality ofbores for bolting the disc subassembly to the base.

In the method of fabrication of the present invention, an outer wallsegment of the drive machine housing is cast to form a base of the brakeassembly. In casting the outer wall segment to form a base of the brakeassembly, a metal blank of higher magnetic permeability is cast orembedded into the casting of the outer wall segment and is machined toform the base. Alternately, the casting of the outer wall segment may bedimensioned and configured so that the casting of the outer wall segmentitself forms the base. The outer wall segment is secured for machining abearing assembly counterbore and, without unsecuring the wall segmentfrom the machining operation, the base of the disc brake assembly ismachined to form the groove for housing a magnetic coil, a plurality ofbores to house the brake springs and a plurality of bolt bores. Preciserelative alignment of the grooves, spring bores, stud bores, and bearingassembly counterbore is efficiently achieved by contemporaneousmachining operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a worm gear elevator drive machine andintegrated brake assembly in accordance with the present invention;

FIG. 2 is a fragmented sectional view of the disc brake assembly of FIG.1;

FIG. 3 is a broken-away sectional view of a helical gear elevator drivemachine.

BEST MODE FOR CARRYING OUT THE INVENTION

Although specific forms of the present invention have been selected forillustration in the drawings, and the following description is drawn inspecific terms for the purpose of describing these forms of theinvention, the description is not intended to limit the scope of theinvention which is defined in the appended claims.

Referring to FIG. 1, a worm gear elevator drive machine is shown andgenerally designated by the numeral 10. The machine 10 generallycomprises a machine or gear box housing 12, worm gear 14, worm wheel 16,output shaft 18 and drive sheave 20. The worm gear 14 meshes with theworm wheel 16 which is keyed directly to the output shaft 18. The shaft18 is journaled in bearings 22, 24 mounted in the walls of the housing12. It is understood that the worm gear 14 is driven by an electricmotor (not shown) which in turn drives the worm wheel 16 and outputshaft 18. The drive sheave 20 is mounted on and keyed to the outputshaft 18 and carries the elevator and counterweight cables. The coverplate 26 is mounted on the end of the output shaft 18 to hold the sheave20 in place on the shaft 18. The above-described components aregenerally conventional to worm gear elevator drive assemblies.

The machine 10 also includes an integrated disc brake assembly generallydesignated by the numeral 28 which comprises a base 30, a magnetic coil32, an armature plate 34 and a disc subassembly 36.

The base 30 is integrally formed with the outer wall section 38 of themachine or gear box housing 12. In the illustrated embodiment, the outerwall section 38 is cast iron and the base 30 is a steel blank which iscast or embedded directly into the wall section 38 and then machinedinto the configuration shown in FIG. 1 as described in detailhereinafter. The bearings 24 are mounted within a counterbore 40 in thebase 30. The bearings 24 are held in place in the counterbore 40 by abearing retainer cover 41 which is fixed to the base 30 by bolts 42. Adouble lip seal 44 mounted to the cover 41 sealingly engages the outputshaft 18 to seal the bearings 24.

The base 30 has an outwardly opening U-shaped annular groove 46concentric about the counterbore 40 and configured to house the magneticcoil 32. The base 30 also contains a plurality of threaded stud bores 48for receiving-studs 50, spring bores 52 for housing springs 54, anddowel bores 56 for receiving dowels 58. The magnetic coil 32 is housedwithin the annular groove 46 and bonded therein by an adhesive orbonding agent such as an epoxy resin. In machining the groove 46, thewalls forming the groove are preferably rough cut to facilitate bondingof the coil within the groove 46. Alternately, the coil 32 may be keyedto the groove 46 to lock the coil in place. Other types of suitablesecurement are also acceptable.

The armature plate 34 is disposed adjacent the magnetic coil 32 and thedisc subassembly 36. The disc subassembly 36 is bolted to the base 30 by(four) studs 50 and nuts 51 and comprises a plurality of interleavedfriction discs 60 and brake plates 62. The outer end of each frictiondisc carries an annular radially outwardly extending friction pad 66.The friction discs 60 are mounted directly to the shaft 18 for rotationby the shaft 18. The outer end of the output shaft 18 has a plurality ofaxially extending splines 64 and the inner ends of the friction discs 60are splined directly to the splines 164 so that the output shaft rotatesthe discs 60.

The armature plate 34 is biased away from the magnetic coil 32 by aplurality of coil springs 54 mounted in base 30. The brake plates 62 arebiased apart by a plurality of light coil springs 68 mounted on thestuds 50 which extend through the armature plate 34 and the brake plates62 (FIG. 2). The brake plates 62 are thus held away from theinterleaving friction discs 60 by the coil springs 68 when the brakeassembly is "off". The nuts 51 are threaded onto the ends of the studs50 so as to allow for adjustment of the spacing between the plates 62 toaccount for wear on the brake during its useful life. A plurality ofguide dowels 58 (not shown in FIG. 1) dispersed circumferentially aboutthe brake assembly 28 extend from the base 30 through the armature plate34 and brake plates 62 to guide axial movement of these componentsrelative to each other when the brake is set and released. It will beappreciated from the above that the discs 60 rotate with the outputshaft and sheave 20, while the plates 62 remain relatively stationary.

The brake assembly described above operates as follows. During normalsafe operation of the elevator, the coil 32 is energized, and thearmature plate 34 is magnetically held against the base 30 causing theactuating springs 54 to be compressed. The brake assembly 28 is thus ina "release" mode, and the friction discs 60 will be free to rotate withthe shaft 18 uninhibited by the plates 62. When braking is required,such as in the event of an unsafe operating episode, e.g., theoccurrence of overspeed in either direction, power to the coil 32 willbe switched off, and the coil 32 will deenergize. The actuating springs54 will then move the armature plate 34 away from the base 30 and towardthe annular brake plates 62. The force of the springs 54 is such thatthe spacer springs 68 will be compressed and the plates 62 will clampthe discs 60 against further movement. Movement of the output shaft 18and sheave 20 will thus be interrupted and the cab will stop itsmovement in the hoistway. At the same time, power to the machine will beinterrupted. After the cause of the unsafe cab movement has beendiscovered, the brake assembly 28 can be released merely by restoringpower to the coil 32. The brake assembly is similarly operable fornormal braking as well as additional unsafe conditions such as toprotect against uncontrolled low speed movement of the elevator. Furthergeneral descriptions of the operation and structure of an elevator drivemachine and disc brakes are found in the above-identified U.S. Pat. No.5,201,821 and U.S. Pat. No. 5,226,508 which are incorporated herein byreference.

As can be appreciated, the disc brake assembly is easily disassembledfor servicing in the field by removal of the four nuts 51. The discs aresplined directly to the outer end of the output shaft and no jacking ofthe output shaft is required to service the brake discs. Brake air gapadjustment is easy to accomplish using a feeler gauge and wrench. Inthis regard, an air gap of 0.5 mm is possible which greatly reduces thenoise level due to normal operation of the brake.

In the illustrated embodiment, the outer wall segment 38 of housing 12is cast iron and the integral base 30 is preferably steel for enhancedmagnetic permeability. Other metals which provide acceptable magneticpermeability characteristics may also be utilized for the base 30. Inthe method of fabrication of the present invention, a steel blank forforming base 30 is cast or embedded directly into the wall segment 38during the casting of wall segment 38. The wall segment 38 is thensecured or bolted down for machining the bearing counterbore 40. Theannular U-shaped groove 46 for housing the magnetic coil 32 is cut inthe steel blank concentrically about the counterbore 40. The side wallsof the U-shaped groove 46 are preferably rough cut to provide anenhanced bonding surface for the adhesive utilized in bonding the coil32 within the groove 46. At this time, the stud bores 48, the springbores 52, and the dowel bores 56 are drilled in the blank to form thebase 30. Upon completion of the machining process, the wall section 38is then unsecured and removed from the cutting machine and thereafterthe magnetic coil is fitted within the groove 46 and bonded in place bya suitable adhesive or bonding agent such as an epoxy resin. Thepreferred method of fabrication is to insert the magnetic coil intogroove 46 and coat the magnetic coil with epoxy resin and cause it tocure thereby bonding the coil in the groove.

Alternately, the blank for forming base 30 may be omitted and the outerwall portion 38 is cast to a predetermined configuration to form a basefor the disc brake assembly. In this configuration, the cast iron wallsection 38 would form the base 30 and would be machined as describedabove to provide the annular groove 46, the threaded stud bores 48, thespring bores 32, the dowel bores 56 and the bearing counterbore 40. Thedimensions and configuration of the base 30 will be determined so as toprovide an acceptable magnetic flux path through the cast iron base 30.

Referring to FIG. 3 wherein identical numerals are utilized to identifylike or similar parts, the integrated brake assembly of the presentinvention is shown in a helical gear elevator drive machine generallydesignated by the numeral 11. As known in the art, the elevator drivemachine 11 has a helical gear drive assembly 74 (not shown in detail)driving an output shaft 76 with a sheave 20 simply supported by bearingassemblies 78, 80 disposed on opposite sides of the sheave 20. Thehousing 23 of machine 11 includes an outer wall segment 38 referred toas a bearing stand. Similar to machine 10, the base 30 is integrallyformed in the wall segment 38. The base 30 has a bearing counterbore 40housing the bearing assembly 80. A retaining nut 82 is threadablymounted on the output shaft 76 to hold the bearing assembly 80 in thecounterbore 40. An annular seal 84 is mounted on the armature plate 34and sealingly engages the outer circumferal surface of the retaining nut82 to seal the bearing assembly 80. The remaining components asindicated by identifying numerals in FIG. 3 are similarly configured andassembled as described in relation to FIG. 1 and need not be describedin further detail for purposes of the alternate embodiment. Similarly,the wall segment 38 and the base 30 are integrally formed and fabricatedin accordance with the above-described method of fabrication.Additionally, the integrated disc brake of the present invention mayalso be utilized in a gearless elevator drive machine having a simplysupported sheave as illustrated in the drive machine 11 of FIG. 3.

As can be appreciated from the foregoing, a new and improved elevatordrive machine and integrated disc brake assembly has been described. Theintegrated brake assembly is cost efficient to manufacture, reduces thenumber of component parts as compared to the prior art and is easy andconvenient to service. In addition, a new and improved method offabricating such an integrated brake assembly has also been described.

As will be apparent to persons skilled in the art, various modificationsand adaptations of the structure above described will become readilyapparent without departure from the spirit and scope of the invention,the scope of which is defined in the appended claim.

What is claimed is:
 1. A method of fabricating the base of a disc brakeassembly of an elevator drive machine having a housing with an outerwall comprising the steps of:casting an outer wall segment of the drivemachine housing to provide a base; securing the outer wall segment formachining operations; cutting a bearing assembly counterbore in saidouter wall segment; cutting a groove for housing a magnetic coil aboutsaid bearing assembly counterbore; drilling a plurality of bores tohouse brake springs and unsecuring the outer wall segment from machiningoperations after said cutting and drilling steps.
 2. The method of claim1 wherein the step of cutting a groove comprises performing a cut ofsufficient roughness to facilitate adhesive mounting of a magnetic coilwithin said annular groove.
 3. The method of claim 2 further comprisingpositioning a magnetic coil within said groove and applying adhesivematerial to the magnetic coil and annular groove to bond the magneticcoil within said groove.
 4. The method of claim 1 wherein the step ofcutting a groove further comprises configuring the groove to provide akeyed interlock with a magnetic coil mounted within the groove.
 5. Themethod of claim 1 comprising drilling a plurality of bolt holes in saidouter wall segment prior to unsecuring the outer wall segment frommachining operations.
 6. The method of claim 1 whereinthe step ofcasting an outer wall segment comprises casting a base element of highermagnetic permeability than said outer wall segment within the outer wallsegment; the step of cutting a bearing assembly counterbore comprisescutting said counterbore in said base element; the step of cutting agroove comprises cutting said groove in said base element and the stepof drilling a plurality of bores comprises drilling said bores in saidbase element.
 7. The method of claim 6 comprising drilling a pluralityof bolt holes in said base element prior to unsecuring the outer wallsegment from machining operations.
 8. A method of fabricating the baseof a disc brake assembly of an elevator drive machine having a housingwith an outer wall comprising the steps of:casting an outer wall segmentof the drive machine housing to provide a base; cutting a beatingassembly counterbore in said outer wall segment; and cutting a groovefor housing a magnetic coil about said bearing assembly counterbore,wherein the step of curing a groove comprises performing a cut ofsufficient roughness to facilitate adhesive mounting of a magnetic coilwithin said groove.
 9. The method according to claim 8, furthercomprising the step of drilling a plurality of bores to house brakesprings.
 10. The method of claim 8, further comprising positioning amagnetic coil within said groove and applying adhesive material to themagnetic coil and groove to bond the magnetic coil within said groove.11. The method of claim 8, comprising drilling a plurality of bolt holesin said outer wall segment.
 12. The method of claim 8 whereinthe step ofcasting an outer wall segment comprises casting a base element of highermagnetic permeability than said outer wall segment within the outer wallsegment; the step of cutting a bearing assembly counterbore comprisescutting said counterbore in said base element; and the step of cutting agroove comprises cutting said groove in said base element.
 13. Themethod according to claim 12, further comprising a step of drilling aplurality of bores in said base element to house brake springs.
 14. Amethod of fabricating the base of a disc brake assembly of an elevatordrive machine having a housing with an outer wall comprising the stepsof:casting an outer wall segment of the drive machine housing to providea base; cutting a bearing assembly counterbore in said outer wallsegment; and cutting a groove for housing a magnetic coil about saidbearing assembly counterbore, wherein the step of cutting a groovefurther comprises configuring the groove to provide a keyed interlockwith a magnetic coil mounted within the groove.
 15. The method accordingto claim 14, further comprising the step of drilling a plurality ofbores to house brake springs.
 16. The method of claim 14, comprisingdrilling a plurality of bolt holes in said outer wall segment.
 17. Themethod of claim 14, whereinthe step of casting an outer wall segmentcomprises casting a base element of higher magnetic permeability thansaid outer wall segment within the outer wall segment; the step ofcutting a bearing assembly counterbore comprises cutting saidcounterbore in said base element; the step of cutting a groove comprisescutting said groove in said base element.
 18. The method according toclaim 17, further comprising a step of drilling a plurality of bores insaid base element to house brake springs.